1. Field of the Invention
The present invention relates to a telecommunication control system allowing a selection of AMR (Adaptive Multi-Rate) connection or UDI (Unrestricted Digital Information) connection on an as required basis in a mobile telecommunication system which carries out telecommunications between portable terminals.
2. Description of the Related Art
In a mobile telecommunication system, a general practice is for a caller to request for a call by selecting an AMR or a UDI at the time of a call. In this case, if a UDI call is transmitted to a terminal incompatible with the UDI, a connection is once interrupted, followed by calling again as an AMR connection (N.B.: there is a terminal with the function of automatically changing over to the AMR).
FIG. 1 exemplifies conventional telecommunication processing in the case of transmitting a UDI call to a portable terminal compatible with a UDI.
A caller terminal transmits a SETUP signal and also a SETUP setting (i.e., a call request category of “UDI”, and terminal capability information of “UDI”) (N.B.: the preposition “of” in front of word(s) in quotation, such as “UDI”, “AMR”, et cetera, is grammatically appositional throughout this specification) to an RNC (Radio Network Controller), and to a caller side CN (Core Network) after establishing an RNC and an RRC (Radio Resource Control) CONNECTION.
Meanwhile, having received a Setup setting, the caller side CN makes a UDI connection readiness established between the caller terminal and RNC, followed by transmitting an IAM signal and also a requested call category of “UDI” to a receiver side CN (i.e., a CN on a receiver side).
Having received the IAM signal, the receiver side CN establishes an RRC CONNECTION between the RNC and a receiver terminal, followed by notifying of a requested call category of “UDI” together with a SETUP signal.
Having received the SETUP signal, the receiver terminal checks the caller call category and transmits a CALL CONFIRM setting (i.e., a response call category of “UDI” and terminal capability information of “UDI”) together with a CALL CONFIRM signal to the receiver side CN.
Having received the CALL CONFIRM setting, the receiver side CN makes a UDI connection readiness established between the RNC and receiver terminal.
As a connection readiness is established between the RNC and receiver terminal, the receiver terminal transmits an ALERT signal, a CONN signal, et cetera, to the receiver side CN and, as the caller terminal returns a CONNACK signal, a UDI connection is completed between the caller terminal and receiver terminal.
FIG. 2 exemplifies conventional telecommunication processing in the case of transmitting a UDI call to a portable terminal incompatible with a UDI.
Having received a SETUP signal, a receiver terminal transmits a CALL CONFIRM setting (i.e., a response call category of “AMR” and terminal capability information of “AMR”) together with a CALL CONFIRM signal to the receiver side CN.
Having received the CALL CONFIRM setting, the receiver side CN checks compatibility between the requested call category and response call category, judges to be incompatible, transmits a request for disconnecting the telecommunication to the caller side CN and also disconnects the telecommunication between the RNC and receiver terminal.
As described above, if an incompatibility occurs between a requested call category and a response call category, a connection must be disconnected once, followed by connecting telecommunication again by a suitable connection configuration since a connection configuration (i.e., AMR or UDI) between an RNC and a receiver terminal is constrained by a requested call category of a caller terminal. As a result, there has been a problem of the load of a telecommunication control system which carries out call controls becoming large.
A Laid-Open Japanese Patent Application Publication No. 07-115634 has disclosed an image telecommunication terminal for facilitating a simple handling of operation keys for setting various operation modes and an easy visual identification of setup various operation modes, thereby attempting improvements of operability and serviceability.
A Laid-Open Japanese Patent Application Publication No. 2000-174839 has disclosed a wireless telecommunication system and a wireless portable terminal for easily changing to a different information transmission capability during communication, thereby performing flexible telecommunication in a wireless telecommunication system which carries out wireless transmissions by a plurality of information transmission capabilities between a base station and a mobile station.
A Laid-Open Japanese Patent Application Publication No. 2001-309086 has disclosed a multimedia telecommunication terminal which makes a receiver side select a telephone conversation either of a videophone channel or a voice-phone channel, thereby changing to a telecommunication channel.
A Laid-Open Japanese Patent Application Publication No. 2002-281175 has disclosed a telecommunication terminal apparatus and a telecommunication control program for implementing smooth telecommunication with a desired correspondent by selecting and/or changing a connection category and telecommunication method appropriately in a multiple telecommunication terminals equipped with a plurality of connection categories and also with one or more telecommunication configurations for each connection category.
A Laid-Open Japanese Patent Application Publication No. 2003-046676 has disclosed a telephone equipped with a videophone function enabling a voice-phone call even in the case of the telephone of an intended part not equipped with a video-phone function without a specific calling operation for the voice-phone call by automatically connecting a line for a voice call if a line connection for the video-phone call is not available.